Sources and Sinks of Greenhouse Gasses (GHG) in Agricultural Soil Ecosystems

Agricultural activities contribute significantly to global climate change by emitting and sequestering greenhouse gases (GHGs). Understanding the sources and sinks of different GHGs in agricultural soil ecosystems is essential for developing effective mitigation strategies. This chapter summarizes the sources and sinks of the three major GHGs emitted from agricultural soil ecosystems: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). CO2, the most prevalent GHG, is released primarily through the respiration of soil microbes, which decompose soil organic matter. Agricultural soils can also sequester CO2 through carbon sequestration, which is facilitated by adding organic matter to the soil and adopting conservation practices that reduce soil disturbance. Methane, a potent GHG, is produced mainly in agricultural soil ecosystems under waterlogged conditions, where anaerobic microbes decompose organic matter. Paddy rice cultivation, livestock farming, and manure management are major sources of methane emissions. Conversely, certain agricultural practices, such as aerobic soil management and improved livestock waste management, can reduce methane emissions and promote methane oxidation. Nitrous oxide, another potent GHG, is emitted from agricultural activities such as nitrogen fertilization, animal waste management, and soil cultivation. Nitrification and denitrification processes contribute to nitrous oxide production and emission. However, efficient nutrient management strategies, including precision fertilization, nitrogen inhibitor use, and optimized irrigation practices, can minimize N2O emissions. To effectively mitigate GHG emissions from agricultural soil ecosystems, it is crucial to have a comprehensive understanding of the sources and sinks of different GHGs. This allows us to target management practices to reduce emissions and enhance carbon sequestration potential. Adoption of sustainable agricultural practices that promote soil health, optimize nutrient management, and reduce reliance on synthetic inputs can mitigate climate change impacts while ensuring agricultural productivity and resilience.